Engine starter



W. L. M GRATH July 15, 1924.-

ENGINE STARTER Filed May 10, 1922 a Sheets-Sheet 4 H ,m M V J 7 July 15, 1924. 1 1,501,172

W. L. M GRATH ENGINE STARTER Filed May 10, 1922 3 SheetsSheet 2 whm 15 lmgn 501,172 FF Q E}.

, WILLIAM L mcenn'rn, or ELMIRA, NEW YORK, ASSIGNOR r ECLIPSE MACHINE COMPANY, or ELMIRA, NEW YORK, A CORPORATION or NEW YORK.'

ENGINE STARTER.

Application filed May 10, 1922. Serial Nb. 559,732.

To all whom it may concern:

Be it known that I, WILLIAM L. Mc- QGRATH, a citizen of the United States, residing at Elmira, in the county of Chemung and State of New York, have invented certain new and useful Improvements in Engine Starters, of which the following is a specification. a

My invention relates to engine starters and to that part thereof known as the drive or transmission, located between the prime mover such as an electric motor and a of the engine to be started such as the flywheel thereof. The drive with which my invention is concerned is of that type exemplified by Bendix Patent No. 1,125,935 issued on January 26, 1915, characterized, among other features, by a coiled drive spring between the driving shaft and the driven .shaft which latter is the screw shaft on which a pinion engaging the fly-wheel ismounted. The object of my invention is to provide means to support'the first coil, preferably at each end, of the drive spring insuch manner as to relieve the fastening means or anchoring screws or bolts fromv flexure or bending loads when the spring winds up in the starting operation, leaving as the only load to be taken by such screws 3 a plain shear load which is easily resisted by such screws. Another resulting advantage is to prevent fatigue of the metal of the screws which is .caused by flexure thereof, inasmuch as such flexure overcome by the use of my invention.

Speakin in its broader aspect, consists in providing means for supporting the first coils of the spring at a suitable point, such as 90 angularly displaced from the anchoring screws, whereby the torque through these coils of the spring will result in a load on the screws at right angles thereto, thereby preventing flexure of such screws. These supporting means may constitute an integral part of the driving and driven heads to which the ends of the drive spring are anchored-but inpra'ctice and for convenience in manufacture, I prefer to provide such means as a separate part or member such as a clip, suitably secured to sand heads.

In the drawings Fig. 1 is an elevation of a starter system illustrating a drive embodyingrmy invention; Fig. 2 another elepart I g in general terms, my invention,

vation showing the parts thereof in section; Fig. 3 is .a sectional plane on the line 33 of F ig-, 2; Figs. 4, 5 and 6 cross-sections -on the corresponding section lines indicated on Fig. 1; Fig. 7 is an end elevation of the supporting clip, looking at one end thereof; Fig. 8 a similar view viewed from the other en Fig. 9 a plan view thereof; Figs. 10 and 11 sections of the clip on the corresponding section lines indicated in Fig. 7 Fig. 12a plan view of the clip in blank form partially completed and before being rolled up or formed as the final clip; Fig. 13 a sectional elevation of a modified form of construction; F i 14 a cross-section on' the line 1414 of igx13; Fig. 15 a sec-o -tional'elevation of another modified form of construction and Fig. 16 a cross section on the line 16-16 of Fig. 15.

It will be understood that niy-invention,

in its broader aspect may partake of differto in so far as the broad claims are concerned. It will also be understood that the supporting means may be and by preference are provided at the end coils at both ends of the drive spring, but that a measure of my invention may be obtained by em-' ploying such supporting means at one end only thereof. ,5 Referring to the embodiment of my invention illustrated in Figs. 1 to 12 and first briefly describing the engine starter structure, the samecomprises an electric motor 1 having an extended armature shaft 2 on which is mounted a hollow screw shaft 3, a pinion 4 adapted to mesh'with the flywheel 5, a driving head 6, and a drive spring 7 whose opposite ends are fastened or anchored to the driving head 6 and to no the driven head 8 of the screw shaft by the screws or studs 9' and 10, res ctively. The supporting means at the en of the drive spring are similar in structure but reversed in position. Each. clip comprises 5 a strip of sheet metal 11 which originally has the form shown in Fig. 12 This strip is provided with a hole 12 through which the screw passes and is also provided with eons 13 and 14 which are inturned so 11c Y as to bear against the inner face of the head to which the clip is applied, thereby preventing displacement or rocking movement of the clip. The longer or'extended end of thestrip is folded twice upon itself so as to form a projection 15 between the first coil and the side of the head to which the clip isv attached, as clearly shown in Figs. 4, 5 and 6. In practice and'by preference the construction and arrangement are such that this projection is located as shown, that is at a point displaced approximately 90 angularly from the anchoring screw.

Inapplying the clip, this is done obviously before the spring and .screws are applied. The clips are placed upon the heads with the hole 12 in register with the screw holes in the heads which holes and screws properly locate the clips-and also secure them in lace. The spring and screws are now applied and this particular assembly is then complete.

- drive the spring winds up,

In the, starting operation of this type of which means that the first coils, in particular, tend to wind down upon the heads.- When my supporting means or clips are employed, the first coils are prevented from winding down close upon the heads, particularly at the point where the projection 15 is located, with the result that the torque transmitted through the spring is at right angles to the longitudinal axis of the screws, merely a shearst'rain or ;.load which can be easily resisted by the screws and that there is no flexure load applied to these screws. Heretofore in this type of drive the resulting load applied to the screws has been the component of a flexure load and a shear load, which tended to bend or break the screws and also cause fatigue therein.

My invention in its broadest aspect may be embodied in quite different structures from that above described, such as are shown in Figs. 13 to 16. As shown in Figs. 4, 5 and 6 the heads are of smaller diameter than the inside diameter of the first coils, but according to the modifiedforms of construction these heads are made of the same diameter asethe first coils of the spring and either the springer the inner portions of the heads are made of special formation in order that the final result will be the supporting of the first coils in such manner that the torquewill result in a load on the anchoring means or screws at right angles thereto, thereby accomplishing the objects of the invention in its broadest aspect.

Referring. to Fig. 13 the driving head 16 and the driven head '17 are made-of the same diameter as the opening through the end'coils of the spring. This spring 18 instead of being a cylindrical helix 1s wound to the form shown in Fig. 13, that is, conical in longitudinal section. As a result the end that is, there is According to the modification of Fig. 15

the driving head 19 and the driven head 20 are also made of the same diameter as the opening through the end coils of the spring 21, but the inner adjacent ends of these heads have reduced tapers 22 and 23, respectively, as shown in Fig. 15. The spring 21 when in normal condition is a helix but in operation the coils on winding down are permitted by such tapered ends of the heads to wind inwardly towards or upon such tapers.

The drive spring is a helical spring and its coils have the cross section shown, that is with a greater height than width. Without the provision of my supporting means, there is considerable lever action of the spring upon the anchoring screws, with the result that the screws are flexed in the winding down of the spring in the cranking operation and are sometimes thereby broken.

My supporting means -avoids any possibility of th's flexure and breakage and the screws are thereby protected.

I claim:

1. In an engine starter drive, a helical drive spring whose coils have a greater height than width in cross section, an anchoring means for an end of such spring, in combination with means for supporting the first coil at such end in such manner as to avoid lever action on such anchoring means and consequent flexurethereof.

2. In an engine starter drive, a helical drive spring whose coils have a greater height than width in cross section, and an anchoring screw engaged by an end of the spring, in combination with means for supporting the first coil-at such end in such manner as to avoid lever action on such screw andconsequent flexure thereof.

3. In an engine starter drive including a 'driving shaft having a drive head, a driven 4. In an engine starter drive including a driving shaft having a drive head, a driven shaft havin a driven head, a driving member mounte on the driven shaft, a helical drive spring whose ,coils have a greater height than width in cross section, and screws for anchoring the ends of the springs to the heads in combination with a support interposed between the end coils of such spring and the heads of-points thereon approximately 90 removed from the connection between the screws and the spring.

5. In an engine starter drive including a driving shaft having a drive head, a driven shaft having a driven head, a driving member mounted on the driven shaft, a helical drive spring whose coils have a" greater height than width in cross section, and screws for anchoring the ends of the springs to the heads in combination with curved clips secured to said heads by said screws and having projections located adjacent the inner surfaces of such end coils for supporting the end coils in such manner as to avoid lever action on the screws and consequent fiexure thereof.

6. In an en ine starter drive including a driving shaft aving a drive head, a driven shaft having a driven head, a driving'member mounted on the driven shaft, a coiled drive spring operatively connecting the two heads, and screws for anchoring the ends of the spring to theheads, in combination with means for supporting the first end coils of the spring to cause the load to act on the screws at right angles to the longitudinal "axes of the screws, said supporting means comprising curved clips secured to said hea s by said screws and having projections located adjacent the inner surfaces of such end 00115, and also having flanges engaging said heads to prevent displacement.

WILLIAM L. MoGRATH. 

